Objective: The fetomaternal interface once thought to be an immune privilege site is now known to harbor a large population of maternal immune cells. NK cells, T cells, dendritic cells and macrophage are all crucial to normal placentation. Neutrophils, a major part of the innate immune system, are absents from the first trimester decidua. Our data shows for the first time that neutrophils, much like other immune cells infiltrate the second trimester decidua.
Study Design: Following informed consent, second trimester deciduas (n>5) were collected from patients during social termination of normal pregnancy. FACS analysis and immunohistochemistry using anti CD66b, CD15 and neutrophil elastase were used to identify neutrophils within decidual tissue. Ex vivo invasion assay was used to demonstrate the interaction between second trimester decidua and peripheral blood neutrophils.
Results: Our FACS analysis shows that 5-15% of the total CD45+ cells (leukocytes) in the second trimester decidua are neutrophils. Decidual neutrophils in oposed to peripheral blood neutrophils express higher level of CD66b, CXCR3, CXCR4 and lower level of the IL-8 receptors CXCR1, CXCR2. Immunohistochemistry staining showed unique distribution of neutrophils within the decidua. Invasion assay confirms that second trimester decidual cells secret soluble factor/s initiating peripheral blood neutrophils extravasation.
Conclusion: These observation are the first to show that unique neutrophil population resident the second trimester decidua. Future studies will address their origin and potential role at the fetomaternal interface.
Hagai Amsalem,1,2, Caroline Dunk,2 Einat Eliraz1 and Stephen J Lye2.
1. Department of Obstetrics and Gynecology, Hadassah-Hebrew University Medical Centers, Mt. Scopus, Jerusalem, Israel.
2. Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.